A joint laboratory effort has begun to provide development of new measures of neurotransmitters and their metabolites as well as more efficient delivery of previously established assays. The bulk of cerebrospinal fluid, plasma and urine assays within the intramural program of the NIMH are analyzed in this facility. Over 5000 samples were analyzed during the last year. Routine analyses include norepinephrine in all tissues, MHPG in CSF, plasma and urine, homovanillic acid and 5HIAA in CSF and plasma, and VMA in urine. Most of these assays can be performed by high performance liquid chromatography (HPLC) although urinary MHPG and VMA still require combined gas chromatography-mass spectrometry. New HPLC assays which have been developed for serotonin, dopamine, epinephrine, and normetanephrine in CSF, epinephrine and DOPAC in plasma and 5HIAA in urine. A GC-MS assay has been developed for normetanephrine. These new assays provide the means of studying interactions between neurotransmitter systems in man as well as distinguishing between differences in metabolism vs turnover.